You may be able to order the item on-line from Silvermans. They have been dealing in surplus military kit for a long time.

(They make, or used to make, a good profit from British Army soldiers. If a soldier lost a piece of kit, he paid the full price for the item. If he ordered it from Silvermans, and presented it to the Quartermaster for exchange, he paid a lot less. Silvermans would then buy the discarded item from the Army for a trifle. I vaguely recall seeing the same revolting piece of Pattern '58 webbing being presented for exchange twice within four months.)

The above is not meant to imply that Silvermans deal entirely in junk. A lot of what appears on their web site appears to be brand new and is probably surplus only because it has been ordered by the forces in excess of actual requirements.